CA2033488A1 - Ceiling mount microwave transceiver with 360 degree radiation pattern - Google Patents
Ceiling mount microwave transceiver with 360 degree radiation patternInfo
- Publication number
- CA2033488A1 CA2033488A1 CA002033488A CA2033488A CA2033488A1 CA 2033488 A1 CA2033488 A1 CA 2033488A1 CA 002033488 A CA002033488 A CA 002033488A CA 2033488 A CA2033488 A CA 2033488A CA 2033488 A1 CA2033488 A1 CA 2033488A1
- Authority
- CA
- Canada
- Prior art keywords
- antenna
- radiation
- waveguide
- microwave
- electromagnetic radiation
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 230000005855 radiation Effects 0.000 title claims abstract description 42
- 230000005404 monopole Effects 0.000 claims abstract description 6
- 230000005540 biological transmission Effects 0.000 claims description 16
- 238000001514 detection method Methods 0.000 claims description 6
- 230000005670 electromagnetic radiation Effects 0.000 claims 10
- 230000000644 propagated effect Effects 0.000 claims 2
- 230000001902 propagating effect Effects 0.000 claims 1
- 238000001228 spectrum Methods 0.000 claims 1
- 239000006185 dispersion Substances 0.000 abstract description 8
- 230000008878 coupling Effects 0.000 description 3
- 238000010168 coupling process Methods 0.000 description 3
- 238000005859 coupling reaction Methods 0.000 description 3
- 239000004020 conductor Substances 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 230000010355 oscillation Effects 0.000 description 2
- 230000001154 acute effect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000000034 method Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
- G01S7/03—Details of HF subsystems specially adapted therefor, e.g. common to transmitter and receiver
- G01S7/032—Constructional details for solid-state radar subsystems
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
- G01S13/04—Systems determining presence of a target
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q13/00—Waveguide horns or mouths; Slot antennas; Leaky-waveguide antennas; Equivalent structures causing radiation along the transmission path of a guided wave
- H01Q13/02—Waveguide horns
Landscapes
- Engineering & Computer Science (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Computer Networks & Wireless Communication (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Waveguide Aerials (AREA)
- Transmitters (AREA)
- Radio Transmission System (AREA)
- Burglar Alarm Systems (AREA)
- Radar Systems Or Details Thereof (AREA)
Abstract
ABSTRACT
A microwave transceiver comprising a Gunn diode microwave radiation source, a Schottky-barrier diode mixer, a closed rectangular waveguide cavity, a coaxial-waveguide joint, and a monopole antenna providing a microwave radiation dispersion/collection pattern occupying a spatial region elevated from and extending radially outward and 360° in azimuth with respect to said antenna, said spatial region having a substantially spatulate radial cross-section.
A microwave transceiver comprising a Gunn diode microwave radiation source, a Schottky-barrier diode mixer, a closed rectangular waveguide cavity, a coaxial-waveguide joint, and a monopole antenna providing a microwave radiation dispersion/collection pattern occupying a spatial region elevated from and extending radially outward and 360° in azimuth with respect to said antenna, said spatial region having a substantially spatulate radial cross-section.
Description
`` ~ 2~33~
- CEILING MOUNT MICROWAVE TRANSCEIVER
WITH 360 DEGREE RAD~ATION PATT~RN
. .
BACKGROUND OF THE INVENTION
1. Field of the Invention The present invention relates to motion detectors, and more particularly, to a microwave transceiver capable of detecting motion within a ~
spatial region extending substantially radially ~; ;
outward and 360 in azimuth with respect thereto.
, . .
1~ 2. DescriPtion of the Related Art Area protection ~ensors and/or intrusion detection systems, such as those used in burglar alarms, typically include presence and/or motion detec~ors. Two general types of detectors are used:
15passive and active. An example of a passive detector is a passive infrared detector which detects the presence and/or motion of infrared radiation within a defined area to be protected.
An example of an active detector is a 20transceiver. The transceiver transmits and receives some form of radiation to detect the presence and/or j~ motion of an object within the defined area to be protected. One example is an acoustic transceiver which transmits and r~ceives acoustic radiation 25(e.g., ultrasonic, SONA~) to perform its detection function. Another example is a microwave transceiver which transmits and receives microwave radiation i (typically frequencies greater than 1 Gigahertz) to -}; perform its detection function.
In a microwave transceiver, the microwave radiation is typically coupled into free space and transmitted by way of a waveguide horn antenna. (See Figure 1.) Such an antenna efectively radiates and :~, ,.'', :
: : :. - , .~: , : .. : . .; .: : ~
. .;: : . : . . . ,..... . . ; - ~.
.. ~ . . - . , .~.... . .. ... .
~\ 2 ~ 3 3 l~ 8 i~ ~
- CEILING MOUNT MICROWAVE TRANSCEIVER
WITH 360 DEGREE RAD~ATION PATT~RN
. .
BACKGROUND OF THE INVENTION
1. Field of the Invention The present invention relates to motion detectors, and more particularly, to a microwave transceiver capable of detecting motion within a ~
spatial region extending substantially radially ~; ;
outward and 360 in azimuth with respect thereto.
, . .
1~ 2. DescriPtion of the Related Art Area protection ~ensors and/or intrusion detection systems, such as those used in burglar alarms, typically include presence and/or motion detec~ors. Two general types of detectors are used:
15passive and active. An example of a passive detector is a passive infrared detector which detects the presence and/or motion of infrared radiation within a defined area to be protected.
An example of an active detector is a 20transceiver. The transceiver transmits and receives some form of radiation to detect the presence and/or j~ motion of an object within the defined area to be protected. One example is an acoustic transceiver which transmits and r~ceives acoustic radiation 25(e.g., ultrasonic, SONA~) to perform its detection function. Another example is a microwave transceiver which transmits and receives microwave radiation i (typically frequencies greater than 1 Gigahertz) to -}; perform its detection function.
In a microwave transceiver, the microwave radiation is typically coupled into free space and transmitted by way of a waveguide horn antenna. (See Figure 1.) Such an antenna efectively radiates and :~, ,.'', :
: : :. - , .~: , : .. : . .; .: : ~
. .;: : . : . . . ,..... . . ; - ~.
.. ~ . . - . , .~.... . .. ... .
~\ 2 ~ 3 3 l~ 8 i~ ~
-2- ~
collects the microwave radiation, however, its ~-radiation dispersion and collection characteri~tics are not omni-directional. In fact, ouch an antenna exhibits a high degree of directivity, i.e., the edges of its radiation dispersion/co'Llection characteristics extend outwardly at ~m acute mutual angle. Thus, such a waveguide antsnna is limited to ;~
less than 180 of coverage in the azimuth.
Although other types of antennas may be used to obtain an omni-directional radiation dispersion/collection pattern, typically they require additional external parts making them larger, more ;
expensive and difficult to align/tune. For example, a reflector type of antenna may be used. But, such an antenna is typically significantly larger and does not provide uniform field strength within the radiated wave. As another example, a multiple element, or array, type of antenna ~ay be used.
However, such an antenna is significantly larger with tighter fabrication tolerances and re~uires a complex signal feeder. ~
; ,' :' SUMMARY OF THE INVENTION
The present invention comprise~ a microwave transceiver and antenna for detecting an intrusion into a defined spatial region. The microwave ;~
transceiver of the present invention comprises a ~- !
microwave radiation generator, a microwave radiation receiver and a housing assembly therefor.
The microwave transceiver housing provides a rectangular waveguide, a shunt to ground reference for the second harmonic (of the transmitted radiation), a ground reference plane for the antenna and a coaxial-waveguide joint for coupling the :,.
, , :
.. ; ;- ~ .~ .. ., . , : , - - . : , : . - , . , . :
: :: . , ~: . . , . .: - , ~ ~ ~ 3 ~
;,:
collects the microwave radiation, however, its ~-radiation dispersion and collection characteri~tics are not omni-directional. In fact, ouch an antenna exhibits a high degree of directivity, i.e., the edges of its radiation dispersion/co'Llection characteristics extend outwardly at ~m acute mutual angle. Thus, such a waveguide antsnna is limited to ;~
less than 180 of coverage in the azimuth.
Although other types of antennas may be used to obtain an omni-directional radiation dispersion/collection pattern, typically they require additional external parts making them larger, more ;
expensive and difficult to align/tune. For example, a reflector type of antenna may be used. But, such an antenna is typically significantly larger and does not provide uniform field strength within the radiated wave. As another example, a multiple element, or array, type of antenna ~ay be used.
However, such an antenna is significantly larger with tighter fabrication tolerances and re~uires a complex signal feeder. ~
; ,' :' SUMMARY OF THE INVENTION
The present invention comprise~ a microwave transceiver and antenna for detecting an intrusion into a defined spatial region. The microwave ;~
transceiver of the present invention comprises a ~- !
microwave radiation generator, a microwave radiation receiver and a housing assembly therefor.
The microwave transceiver housing provides a rectangular waveguide, a shunt to ground reference for the second harmonic (of the transmitted radiation), a ground reference plane for the antenna and a coaxial-waveguide joint for coupling the :,.
, , :
.. ; ;- ~ .~ .. ., . , : , - - . : , : . - , . , . :
: :: . , ~: . . , . .: - , ~ ~ ~ 3 ~
;,:
3~
transmitted and received microwave radiation between the rectangular waveguide and antenna.
The antenna radiates the transmitted microwave radiation and collects the received microwave radiation. The antenna is a monopole which provide for transmission and reception of ~icrowave ;~
radiation within a spatial region extending substantially radially outward and 360 in azimuth ;~
with respect to the major axis of the antenna, with the spatial region having a substantially spatulate radial cross-section. ;~
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a perspective view of a prior art microwave tran~ceiver and antenna.
Fig. 2 is a cut-away perspective view of a preferred embodiment of the microwave transceiver and antenna of the present invention.
Fig. 3A is a planar, cross-sectional side view of the energy radiation/reception pattern of the --;
antenna of the present invention.
Fig. 3B is a planar, cross-sectional top view of the energy radiation/reception pattern of the s~ antenna of the present invention.
Fig. 3C is a cut-away perspective view of ~
the energy radiation/reception pattern of the antenna - ;
o~ the present invention. ; ;
. ~: '.
~ETAILED DESCRIPTION OF THE INVENTION
Fig. 2 illustrates a preferred embodiment 10 of the present invention. This cut-away perspective view shows the typical primary components used in the present invention. ~hese components include a section o~ closed rectangular waveguide 12, ' a microwave tuning 6crew 1~, a Gunn diode 16, a ;~
:, .
;.,. ' " `: '; ' :- ' ' `, : ~: . ' ' , ~ ' ' . :
2 ~
~4-~ATENT
Schottky-barrier diode l~ and an antenna a sembly 20.
The waveguide 12, tuning 6crew 1~ ancl diodes 16,1~
are quite common in the microwave field and are well known in the art. The antenna assembly 20 i~ -~
described in more detail below.
One lead 22 of the Gunn diode 16 is ;~<
electrically terminated by the lower wall 2~ ~e.g., ~
via conductive clamp) of the wave~uide 12. The other ~;
lead 26 is connected to an external source of DC ~;;-power (not shown) by way of an external wire 2 This lead 26 reaches the wire 28 by passing through `
the top wall 30 o~ the waveguide 12 via a dielectric I~
feed-through 32. With DC power applied, the Gunn ~ ~-diode 16 becomes a microwave oscillator forming a microwave signal source, well known in the art. `
The frequency of oscillation of the 'I microwave radiation emanating ~rom the Gunn diode 16 is determined by the size and dimensions of the cavity 3~ lying between the Gunn diode 16 and the closest internal walls of the waveguide 12. The dimensions and size of this cavity 3~ are preselected ~ -according to methods well known in the art so as to cause the Gunn diode lC to provide the correct signal frequency. To allow for manufacturing tolerance effects, a tuning screw 14 i8 included so as to fine ;~
tune the dimensions of the cavity 3~, thereby fine tuning the frequency of oscillation of the microwave radiation emanating from the Gunn diode 16. During fiignal transmission, this microwave radiation ;~
,~ 30 propagates within the waveguide 12 in the direction ~;
o~ the antenna assembly 20.
1j The antenna assembly 20 includes a - conductive pickup 36, an insulating support 38, a matching section ~0 and an electromagnetic radiator ~2. The pickup 36 and insulating support 38, in . .
,.,, `;
. , : - , :: : :. . .
. ,"'. '' '' , ' , ` ' . ' 1 i . ' :
. :,, ' . -; , . . . ; . . :
S~ ~ 3 ~
., :.
PATENT
conjunction with the waveguide ~2, comprise a coaxial-waveguide joint. ~his joint provides the interface between the two propagation media for the - microwave radiation, namely the waveguide 12 and the coaxial transmission line formed by the pickup 36 and insulating support 38. As described below, this -joint provides for the coupling of microwave radiation into and out of the waveguide 12.
The cavity 4~ comprising the region bounded by the conductive pickup 36 and the closest internal walls of the waveguide 12 acts as a second harmonic filter. The linear distance between the pickup 36 and the nearest end vertical waveguide wall 46 is :. .
made substantially equal to one fourth of the wavelength o~ the desired transmission signal ; frequency. Since this wall 4C ~s electrically conductive and eleckrically connected directly to the s other walls of the waveguide 12, it serves as a ~uarter-wavelength shorted stub. Thus, at the fundamental transmission signal frequency this wall appears to be an open termination, while at the ~econd harmonic of the desired frequency, it serves as a shorted termination, thereby substantially ~ ;
shunting the undesired second harmonic of the ; 25 transmission signal directly to ground reference.
The length of the conductive pickup 36, i.e., the depth of its protrusion into the waveguide 12, is set so as to cause the coaxial-waveguide joint (described above) to provide an in~erface having a low voltage-standing-wave-ratio (VSWR), thereby providing for maximum signal power transfer. The ~
reguisite length for the pickup 36 may be determined `
;. `
theoretically by means well known in the art or `~`
empirically by other means well known in the art ;~`
(e.g., VSWR measurement, signal power measurement). ~
.; .
' :~
.
' ' .'9;' ' . ' ' . ` ` , ' i ' ` , `,. '~ ~ , ` , .',;
~ 3 ~
-6~
PATENT
The transmitted signal exits the waveguide 12 by way o~ the coaxial medium formed by the pickup ~;
36 and insulating support 38 which extend through the -~
lower wall 24 of the waveguide 12. From there the signal goes to the radiator ~2 by way of a matching -; ;
section 4D. The matching section 40 substantially matches the coaxial impedance (50 ohms nominal) to ~ the radiator impedance (approximately 30 ohms~. The ; matching section 40 is merely an electrical extension ` -~
of the conductive pickup 36 without the surrounding insulated support 38. The length of conductor forming the matching section ~0 introduces inductance in series with the coaxial and radiator impedances, thereby providing a substantial impedance match ;~
therebetween. Thus, substantially all signal power is effectively coupled to the radiator 42 ~or ;
transmission (i.e., radiation).
The radiator ~2 is a cylindrical conductor, which may be hollow or ~olid. ~he cylindrical length of the radiator ~2 is made substantially equal to one ; quarter ("1/4") of the wavelength of the desired transmission frequency. m e cylindrical diameter of `
the radiator 42, as compared to the cylindrical ;~
lengthl determines the bandwidth of the radiator 42. ~;
In a prsferred embodiment of the present invention, the diameter is selected to be equal to approximately one-seventh ~"1/7") of the cylindrical length of the ; radiator ~2. Thi~ provides sufficient radiator ~2 bandwidth to allow operation over the permitted frequency range. It will be readily appreciated by ; one skilled in the art, however, that other length~
diameter ratios may be selected to achieve different bandwidths.
During signal reception, the path ~or the incoming signa} is simply reversed from that of the ,.:, . i :, :
~,, : , . . .. . . .
~ 2 ~ g ~ :
PATENT
transmitted signal. The radiator 42 serve~ as a receiving antenna, collecting microw2lve radiation and sending it via the matching section ~lO to the conductive pickup 36 which now serves to couple the ~ 5 received radiati~n into the wavegNidea 12.
- This received radiation propagates wi~hin the waveguide 12 to the Schottky-barrier diode 18, ~ wherein it is non-linearally mixed with the reference ;
; signal generated by the Gunn diode 16 Sdiscussed above). This mixing produces a low intermediate ~-frequency (IF) signal.
One lead ~8 G~ the Schottky diode 18 is terminated electrically by the lower wall 24 ~e.g., via conductive clamp) o~ the waveguide 12. The other ;
; 15 lead 50 i5 connected electrically to an external wire 52 which leads to external processing circuitry Sq.
The lead 50 reaches the wire 52 by way of an insulated feed-through 56 in the top wall 30 of the ~ waveguide 12. The IF signal produced within the i' 20 Schottky-barrier diode 18 (discussed above) is -processed by the external processing circuitry 54, ~ ;
getting there by way of the lead 50 and wire 52. In a preferred e~bodiment of the present invention, the ;~
frequency of this IF signal will typically range between one-half and 100 Hertz.
The processing circuitry 5~ may be intrusion detection circuitry which is well known in the art. Such circuitry analyzes the IF signal and `~
detects whether an intrusion (e.g., presence or motion of an object) has occurred within the spatial -~
region irradiated by the transmitted radiation.
The linear distance separating the diodes -~
16,18 within the waveguide 12 is dependent upon the electrical characteristics of the diodes lC,1~.
Typically, this distance will be determined , .
.. , " , . , , ., ~ . . - , ~ . . , 3 3 ~
` ~LENT
- empirically by varying this distance until the power coupling of the signal produced by the Gunn diode 16 ; into the Schottky-barrier diode 18 is maximized.
i~ This substantially reconciles the dissimilar `- 5 electrical characteristics of the diodes 16,1~
`~ thereby making them compatible. Once this distance has been empirically determined, it need not be ;;`~
adjusted, provided the electrical characteristics of ` the diodes lC,18 do not vary ~ignificantly. In a preferred embodiment of the present invention, this distance will typically be in the range of one-fourth to one-third of the wavelength of the desired signal.
Fig. 3A illustrates a planar cross-sectional view of the radiation dispersion/collection : .
pattern of the radiator ~2 of the present invention.
, The cross-sectional regions 60,62 of radiation ~ dispersion (or radiation collection if the radiator 3^ ~2 is used as a receiving antenna) are illustrated as being spatulately shaped (i.e., similar to a spatula ~ -~
20; or spoon) and oriented in a downward direction as if the radiator 42 were disposed relative to the waveguide 12 as shown in Fig. 2. This orientation results when the bottom surface of the waveguide 12 from which the matching section ~0 and radiator ~2 extend (or some other equivalent surface) serves as the grounded reference plane for the radiator ~2.
This type of antenna-ground reference plane configuration is well ~nown in the art as a monopole antenna over a ground plane.
Fig. 3B illustrates the ~ame radiation dispersion/collection pattern about the radiator 42 when viewed from above the radiator 42 looking downward. This cross-sectional region 6~ is substantially circular, representing the 360 azimuthal characteristic of the pattern.
.
~: 9 :~
PAT~NT
Fig. 3C also illustrate~ the same radiation ` . dispersion/collection pattern when viewed in a cut-away perspective manner.
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transmitted and received microwave radiation between the rectangular waveguide and antenna.
The antenna radiates the transmitted microwave radiation and collects the received microwave radiation. The antenna is a monopole which provide for transmission and reception of ~icrowave ;~
radiation within a spatial region extending substantially radially outward and 360 in azimuth ;~
with respect to the major axis of the antenna, with the spatial region having a substantially spatulate radial cross-section. ;~
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a perspective view of a prior art microwave tran~ceiver and antenna.
Fig. 2 is a cut-away perspective view of a preferred embodiment of the microwave transceiver and antenna of the present invention.
Fig. 3A is a planar, cross-sectional side view of the energy radiation/reception pattern of the --;
antenna of the present invention.
Fig. 3B is a planar, cross-sectional top view of the energy radiation/reception pattern of the s~ antenna of the present invention.
Fig. 3C is a cut-away perspective view of ~
the energy radiation/reception pattern of the antenna - ;
o~ the present invention. ; ;
. ~: '.
~ETAILED DESCRIPTION OF THE INVENTION
Fig. 2 illustrates a preferred embodiment 10 of the present invention. This cut-away perspective view shows the typical primary components used in the present invention. ~hese components include a section o~ closed rectangular waveguide 12, ' a microwave tuning 6crew 1~, a Gunn diode 16, a ;~
:, .
;.,. ' " `: '; ' :- ' ' `, : ~: . ' ' , ~ ' ' . :
2 ~
~4-~ATENT
Schottky-barrier diode l~ and an antenna a sembly 20.
The waveguide 12, tuning 6crew 1~ ancl diodes 16,1~
are quite common in the microwave field and are well known in the art. The antenna assembly 20 i~ -~
described in more detail below.
One lead 22 of the Gunn diode 16 is ;~<
electrically terminated by the lower wall 2~ ~e.g., ~
via conductive clamp) of the wave~uide 12. The other ~;
lead 26 is connected to an external source of DC ~;;-power (not shown) by way of an external wire 2 This lead 26 reaches the wire 28 by passing through `
the top wall 30 o~ the waveguide 12 via a dielectric I~
feed-through 32. With DC power applied, the Gunn ~ ~-diode 16 becomes a microwave oscillator forming a microwave signal source, well known in the art. `
The frequency of oscillation of the 'I microwave radiation emanating ~rom the Gunn diode 16 is determined by the size and dimensions of the cavity 3~ lying between the Gunn diode 16 and the closest internal walls of the waveguide 12. The dimensions and size of this cavity 3~ are preselected ~ -according to methods well known in the art so as to cause the Gunn diode lC to provide the correct signal frequency. To allow for manufacturing tolerance effects, a tuning screw 14 i8 included so as to fine ;~
tune the dimensions of the cavity 3~, thereby fine tuning the frequency of oscillation of the microwave radiation emanating from the Gunn diode 16. During fiignal transmission, this microwave radiation ;~
,~ 30 propagates within the waveguide 12 in the direction ~;
o~ the antenna assembly 20.
1j The antenna assembly 20 includes a - conductive pickup 36, an insulating support 38, a matching section ~0 and an electromagnetic radiator ~2. The pickup 36 and insulating support 38, in . .
,.,, `;
. , : - , :: : :. . .
. ,"'. '' '' , ' , ` ' . ' 1 i . ' :
. :,, ' . -; , . . . ; . . :
S~ ~ 3 ~
., :.
PATENT
conjunction with the waveguide ~2, comprise a coaxial-waveguide joint. ~his joint provides the interface between the two propagation media for the - microwave radiation, namely the waveguide 12 and the coaxial transmission line formed by the pickup 36 and insulating support 38. As described below, this -joint provides for the coupling of microwave radiation into and out of the waveguide 12.
The cavity 4~ comprising the region bounded by the conductive pickup 36 and the closest internal walls of the waveguide 12 acts as a second harmonic filter. The linear distance between the pickup 36 and the nearest end vertical waveguide wall 46 is :. .
made substantially equal to one fourth of the wavelength o~ the desired transmission signal ; frequency. Since this wall 4C ~s electrically conductive and eleckrically connected directly to the s other walls of the waveguide 12, it serves as a ~uarter-wavelength shorted stub. Thus, at the fundamental transmission signal frequency this wall appears to be an open termination, while at the ~econd harmonic of the desired frequency, it serves as a shorted termination, thereby substantially ~ ;
shunting the undesired second harmonic of the ; 25 transmission signal directly to ground reference.
The length of the conductive pickup 36, i.e., the depth of its protrusion into the waveguide 12, is set so as to cause the coaxial-waveguide joint (described above) to provide an in~erface having a low voltage-standing-wave-ratio (VSWR), thereby providing for maximum signal power transfer. The ~
reguisite length for the pickup 36 may be determined `
;. `
theoretically by means well known in the art or `~`
empirically by other means well known in the art ;~`
(e.g., VSWR measurement, signal power measurement). ~
.; .
' :~
.
' ' .'9;' ' . ' ' . ` ` , ' i ' ` , `,. '~ ~ , ` , .',;
~ 3 ~
-6~
PATENT
The transmitted signal exits the waveguide 12 by way o~ the coaxial medium formed by the pickup ~;
36 and insulating support 38 which extend through the -~
lower wall 24 of the waveguide 12. From there the signal goes to the radiator ~2 by way of a matching -; ;
section 4D. The matching section 40 substantially matches the coaxial impedance (50 ohms nominal) to ~ the radiator impedance (approximately 30 ohms~. The ; matching section 40 is merely an electrical extension ` -~
of the conductive pickup 36 without the surrounding insulated support 38. The length of conductor forming the matching section ~0 introduces inductance in series with the coaxial and radiator impedances, thereby providing a substantial impedance match ;~
therebetween. Thus, substantially all signal power is effectively coupled to the radiator 42 ~or ;
transmission (i.e., radiation).
The radiator ~2 is a cylindrical conductor, which may be hollow or ~olid. ~he cylindrical length of the radiator ~2 is made substantially equal to one ; quarter ("1/4") of the wavelength of the desired transmission frequency. m e cylindrical diameter of `
the radiator 42, as compared to the cylindrical ;~
lengthl determines the bandwidth of the radiator 42. ~;
In a prsferred embodiment of the present invention, the diameter is selected to be equal to approximately one-seventh ~"1/7") of the cylindrical length of the ; radiator ~2. Thi~ provides sufficient radiator ~2 bandwidth to allow operation over the permitted frequency range. It will be readily appreciated by ; one skilled in the art, however, that other length~
diameter ratios may be selected to achieve different bandwidths.
During signal reception, the path ~or the incoming signa} is simply reversed from that of the ,.:, . i :, :
~,, : , . . .. . . .
~ 2 ~ g ~ :
PATENT
transmitted signal. The radiator 42 serve~ as a receiving antenna, collecting microw2lve radiation and sending it via the matching section ~lO to the conductive pickup 36 which now serves to couple the ~ 5 received radiati~n into the wavegNidea 12.
- This received radiation propagates wi~hin the waveguide 12 to the Schottky-barrier diode 18, ~ wherein it is non-linearally mixed with the reference ;
; signal generated by the Gunn diode 16 Sdiscussed above). This mixing produces a low intermediate ~-frequency (IF) signal.
One lead ~8 G~ the Schottky diode 18 is terminated electrically by the lower wall 24 ~e.g., via conductive clamp) o~ the waveguide 12. The other ;
; 15 lead 50 i5 connected electrically to an external wire 52 which leads to external processing circuitry Sq.
The lead 50 reaches the wire 52 by way of an insulated feed-through 56 in the top wall 30 of the ~ waveguide 12. The IF signal produced within the i' 20 Schottky-barrier diode 18 (discussed above) is -processed by the external processing circuitry 54, ~ ;
getting there by way of the lead 50 and wire 52. In a preferred e~bodiment of the present invention, the ;~
frequency of this IF signal will typically range between one-half and 100 Hertz.
The processing circuitry 5~ may be intrusion detection circuitry which is well known in the art. Such circuitry analyzes the IF signal and `~
detects whether an intrusion (e.g., presence or motion of an object) has occurred within the spatial -~
region irradiated by the transmitted radiation.
The linear distance separating the diodes -~
16,18 within the waveguide 12 is dependent upon the electrical characteristics of the diodes lC,1~.
Typically, this distance will be determined , .
.. , " , . , , ., ~ . . - , ~ . . , 3 3 ~
` ~LENT
- empirically by varying this distance until the power coupling of the signal produced by the Gunn diode 16 ; into the Schottky-barrier diode 18 is maximized.
i~ This substantially reconciles the dissimilar `- 5 electrical characteristics of the diodes 16,1~
`~ thereby making them compatible. Once this distance has been empirically determined, it need not be ;;`~
adjusted, provided the electrical characteristics of ` the diodes lC,18 do not vary ~ignificantly. In a preferred embodiment of the present invention, this distance will typically be in the range of one-fourth to one-third of the wavelength of the desired signal.
Fig. 3A illustrates a planar cross-sectional view of the radiation dispersion/collection : .
pattern of the radiator ~2 of the present invention.
, The cross-sectional regions 60,62 of radiation ~ dispersion (or radiation collection if the radiator 3^ ~2 is used as a receiving antenna) are illustrated as being spatulately shaped (i.e., similar to a spatula ~ -~
20; or spoon) and oriented in a downward direction as if the radiator 42 were disposed relative to the waveguide 12 as shown in Fig. 2. This orientation results when the bottom surface of the waveguide 12 from which the matching section ~0 and radiator ~2 extend (or some other equivalent surface) serves as the grounded reference plane for the radiator ~2.
This type of antenna-ground reference plane configuration is well ~nown in the art as a monopole antenna over a ground plane.
Fig. 3B illustrates the ~ame radiation dispersion/collection pattern about the radiator 42 when viewed from above the radiator 42 looking downward. This cross-sectional region 6~ is substantially circular, representing the 360 azimuthal characteristic of the pattern.
.
~: 9 :~
PAT~NT
Fig. 3C also illustrate~ the same radiation ` . dispersion/collection pattern when viewed in a cut-away perspective manner.
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Claims (14)
1. An improvement in an apparatus for the transmission and reception of electromagnetic radiation, said apparatus having generator means for generating transmitted electromagnetic radiation for transmission at a transmission frequency, cavity means for propagating said transmitted radiation in a waveguide mode, and reception means for receiving and converting received electromagnetic radiation into a received electrical signal, wherein said improvement comprises:
antenna means for radiating said transmitted radiation and collecting said received radiation within a spatial region elevated from and extending substantially radially outward and 360° in azimuth with respect to said antenna means, said spatial region having a substantially spatulate radial cross-section;
pickup mean electrically connected to said antenna means and positioned within said cavity means for receiving and converting said propagated transmitted radiation from said waveguide mode to a coaxial mode and for converting said collected received radiation from a coaxial propagation mode to a waveguide propagation mode; and filter means for substantially shunting to ground reference said propagated transmitted radiation comprising substantially the second harmonic of said transmission frequency.
antenna means for radiating said transmitted radiation and collecting said received radiation within a spatial region elevated from and extending substantially radially outward and 360° in azimuth with respect to said antenna means, said spatial region having a substantially spatulate radial cross-section;
pickup mean electrically connected to said antenna means and positioned within said cavity means for receiving and converting said propagated transmitted radiation from said waveguide mode to a coaxial mode and for converting said collected received radiation from a coaxial propagation mode to a waveguide propagation mode; and filter means for substantially shunting to ground reference said propagated transmitted radiation comprising substantially the second harmonic of said transmission frequency.
2. An active intrusion detection system, comprising:
generator means for generating electromagnetic radiation for transmission at a transmission frequency;
receiver means for receiving electromagnetic radiation;
housing means for containing said generator and convertor means; and antenna means for radiating said transmitted electromagnetic radiation and collecting said received electromagnetic radiation within a spatial region elevated from and extending substantially radially outward and 360° in azimuth with respect to said antenna means, said spatial region having a substantially spatulate radial cross-section.
generator means for generating electromagnetic radiation for transmission at a transmission frequency;
receiver means for receiving electromagnetic radiation;
housing means for containing said generator and convertor means; and antenna means for radiating said transmitted electromagnetic radiation and collecting said received electromagnetic radiation within a spatial region elevated from and extending substantially radially outward and 360° in azimuth with respect to said antenna means, said spatial region having a substantially spatulate radial cross-section.
3. An apparatus as defined in Claim 2, further comprising processing means for processing said received electromagnetic radiation into an electrical signal indicative of a detection of an intrusion.
4. An apparatus as defined in Claim 3, wherein said transmitted and received electromagnetic radiation lies substantially within the microwave frequency range of the electromagnetic spectrum.
5. An apparatus as defined in Claim 3, wherein said generator means comprises a Gunn diode.
6. An apparatus as defined in Claim 3, wherein said receiver means comprises a Schottky-barrier diode.
7. An apparatus as defined in Claim 3, wherein said housing means comprises a closed rectangular waveguide having inner and outer walls.
8. An apparatus as defined in Claim 7, wherein said rectangular waveguide comprises a tuning cavity for tuning said transmission frequency, a matching cavity for substantially reconciling the respective electrical characteristics of said generator and receiver means, and a filter cavity for substantially shunting to ground reference said transmitted radiation comprising the second harmonic of said transmission frequency.
9. An apparatus as defined in Claim 3, wherein said antenna means comprises a monopole antenna.
10. An apparatus as defined in Claim 7, wherein said antenna means comprises a monopole antenna electrically coupled to said rectangular waveguide by way of a coaxial-waveguide joint, said antenna extending outwardly from and substantially normal to an outer wall of said waveguide, and the outer surface of said outer wall comprising a ground plane reference for said antenna.
11. An apparatus for sensing a physical intrusion into a defined spatial region, comprising:
a microwave transceiver and a microwave antenna having an electromagnetic radiation pattern elevated from and extending substantially radially outward and 360° in azimuth with respect to said antenna, said pattern having a substantially spatulate radial cross-section.
PATENT
a microwave transceiver and a microwave antenna having an electromagnetic radiation pattern elevated from and extending substantially radially outward and 360° in azimuth with respect to said antenna, said pattern having a substantially spatulate radial cross-section.
PATENT
12. An apparatus as defined in Claim 11, wherein said microwave transceiver comprises a Gunn diode and a Schottky-barrier diode.
13. An apparatus as defined in Claim 11, wherein said microwave antenna comprises a monopole antenna.
14. An apparatus as defined in Claim 13, wherein said microwave transceiver comprises a microwave generator, a microwave receiver, a closed rectangular waveguide, a coaxial-waveguide joint, and an antenna ground plane reference.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US07/487,413 US5023594A (en) | 1990-03-01 | 1990-03-01 | Ceiling mount microwave transceiver with 360 degree radiation pattern |
| US07/487,413 | 1990-03-01 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2033488A1 true CA2033488A1 (en) | 1991-09-02 |
Family
ID=23935628
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002033488A Abandoned CA2033488A1 (en) | 1990-03-01 | 1991-01-02 | Ceiling mount microwave transceiver with 360 degree radiation pattern |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US5023594A (en) |
| EP (1) | EP0444357A3 (en) |
| JP (1) | JPH04227597A (en) |
| CN (1) | CN1054513A (en) |
| AU (2) | AU6929291A (en) |
| CA (1) | CA2033488A1 (en) |
| WO (1) | WO1991013414A1 (en) |
Families Citing this family (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2263360B (en) * | 1992-01-06 | 1996-02-07 | C & K Systems Inc | Improvements in or relating to antennas |
| US5583523A (en) * | 1992-01-06 | 1996-12-10 | C & K Systems, Incorporation | Planar microwave tranceiver employing shared-ground-plane antenna |
| EP0607044B1 (en) * | 1993-01-13 | 1999-08-11 | Honda Giken Kogyo Kabushiki Kaisha | Dielectric waveguide mixer and dielectric waveguide radar module |
| US5491467A (en) * | 1994-01-31 | 1996-02-13 | C & K Systems, Inc. | Location independent intrusion detection system |
| US5543799A (en) * | 1994-09-02 | 1996-08-06 | Zircon Corporation | Swept range gate radar system for detection of nearby objects |
| US5905455A (en) * | 1995-08-11 | 1999-05-18 | Zircon Corporation | Dual transmitter visual display system |
| JP3163981B2 (en) * | 1996-07-01 | 2001-05-08 | 株式会社村田製作所 | Transceiver |
| IL121285A (en) * | 1997-07-11 | 2000-02-29 | Visonic Ltd | Intrusion detection systems employing active detectors |
| US6816040B1 (en) * | 2003-04-28 | 2004-11-09 | Spx Corporation | Broadband rigid coaxial transmission line |
| US9379437B1 (en) | 2011-01-31 | 2016-06-28 | Ball Aerospace & Technologies Corp. | Continuous horn circular array antenna system |
| US8648768B2 (en) | 2011-01-31 | 2014-02-11 | Ball Aerospace & Technologies Corp. | Conical switched beam antenna method and apparatus |
| CN104204743B (en) | 2011-11-16 | 2017-04-12 | 泰科消防及安全有限公司 | Motion detection system and method |
| US9482708B2 (en) | 2013-01-29 | 2016-11-01 | ETS-Lindgren Inc. | Enhanced reverberation chamber |
| US9746423B2 (en) | 2013-05-15 | 2017-08-29 | ETS-Lindgren Inc. | Reverberation chamber loading |
| CN109891216A (en) * | 2016-04-12 | 2019-06-14 | 镜元科技股份有限公司 | Large aperture Terahertz-girz lens systems |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3509572A (en) * | 1966-12-08 | 1970-04-28 | Sylvania Electric Prod | Waveguide fed frequency independent antenna |
| FR2305740A1 (en) * | 1975-03-26 | 1976-10-22 | Radiotechnique Compelec | MINI-RADAR ANTI-INTRUSIONS |
| FR2359522A1 (en) * | 1976-07-20 | 1978-02-17 | Thomson Csf | TRANSITION BETWEEN A COAXIAL LINE AND A WAVE GUIDE, AND HYPERFREQUENCY CIRCUITS INCLUDING SUCH A TRANSITION |
| GB1573300A (en) * | 1977-03-09 | 1980-08-20 | Aei Semiconductors Ltd | Microwave oscillators |
| JPS5491079U (en) * | 1977-12-09 | 1979-06-27 | ||
| GB2092853B (en) * | 1981-02-11 | 1985-03-20 | Racal Mesl Ltd | Radar doppler intruder detector |
| JPH0648761B2 (en) * | 1986-11-14 | 1994-06-22 | 島田理化工業株式会社 | Coaxial waveguide converter for orthogonal dual polarization |
| JPS63199508A (en) * | 1987-02-13 | 1988-08-18 | Sharp Corp | Amplifier circuit for low noise microwave |
| JPS6428578A (en) * | 1987-07-23 | 1989-01-31 | Weston Corp | Radar detector/crime preventor for vehicle |
-
1990
- 1990-03-01 US US07/487,413 patent/US5023594A/en not_active Expired - Lifetime
- 1990-12-21 EP EP19900314090 patent/EP0444357A3/en not_active Withdrawn
-
1991
- 1991-01-02 CA CA002033488A patent/CA2033488A1/en not_active Abandoned
- 1991-01-10 AU AU69292/91A patent/AU6929291A/en not_active Abandoned
- 1991-01-17 JP JP3106301A patent/JPH04227597A/en active Pending
- 1991-02-01 CN CN91100709.1A patent/CN1054513A/en active Pending
- 1991-02-26 WO PCT/US1991/001351 patent/WO1991013414A1/en unknown
- 1991-02-26 AU AU77498/91A patent/AU7749891A/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| EP0444357A2 (en) | 1991-09-04 |
| AU7749891A (en) | 1991-09-18 |
| WO1991013414A1 (en) | 1991-09-05 |
| EP0444357A3 (en) | 1992-05-27 |
| US5023594A (en) | 1991-06-11 |
| CN1054513A (en) | 1991-09-11 |
| JPH04227597A (en) | 1992-08-17 |
| AU6929291A (en) | 1991-09-05 |
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Legal Events
| Date | Code | Title | Description |
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| FZDE | Discontinued |